1. Field of the Invention
This invention relates to a dry gas meter of the kind in which flexible diaphragms work back-and-forth in chambers to which the gas being metered is alternately admitted and exhausted. It is desired that meters of the kind described should be made adaptable to different mounting configurations, so that they may be used to replace meters in existing installations.
2. Discussion of the Prior Art
Gas meters are known, for example from DE-C-733288, DE-A-1473042, CH-A-298931, FR-A-1317938 and GB-A-819765, which are adaptable to different configurations. This is normally done by having alternative top covers, each with an inlet and outlet with the inlet and outlet having different configurations. These meters are not adapted to be inserted in a vertical pipe system without excessive pipe bends since they have no facility for inletting gas to the bottom of the meter.
The present invention provides a dry gas meter of the kind in which flexible diaphragms work back and forth in first and second chambers to which the gas being metered is alternately admitted and exhausted, the meter having covers providing inlet and outlet connections for connecting the meter into a gas line and by their configuration determining the path taken by gas flowing through the meter, the meter having a core defining at least parts of the first and second chambers which are located at opposite sides of the meter and a third chamber at the top of the meter, the third chamber accommodating valves and valve drive gear associated with the first and second chambers, characterised in that the core is provided in one piece and additionally defines a fourth chamber at the bottom of the meter and defines internal gasways connecting the third and fourth chambers, and in that in one configuration the covers comprise first and second covers respectively closing the third and fourth chambers and each defining an inlet/outlet connection, which inlet/outlet connections are parallel with one another, and in another configuration the covers comprise third and fourth covers, the third cover closing the third chamber and defining two inlet/outlet connections spaced apart from one another and for connection to two spaced parallel pipes and the fourth cover closing the fourth chamber and having no inlet/outlet connection.
By selecting appropriate first and second covers the meter may in a first mode be adapted for an in-line vertical gas flow from an inlet boss in the lower cover to an outlet boss in the upper cover. In this adaptation, the outlet boss is connected to an exhaust tube connected to the first and second chambers and the inlet boss directs gas flow into the fourth chamber, through the internal gasways and into the said third chamber.
By the simple provision of appropriate upper and lower covers the meter can be adapted to meet a variety of different connection configurations, so that it can be used for vertical in-line connections and for replacement of meters having horizontally spaced-apart connections. It should be noted that the majority of the meter is not affected by such adaptation so that virtually the same design of meter can be used for a number of different applications simply by the use of appropriate covers.
The invention extends to the provision of a meter which can by the selection of simple and appropriate covers be adapted to different connection configurations. It also extends to the provision of a meter having interchangeable covers which affect the direction of gas flow through the meter.